The compound 1-(p-chlorobenzhydryl)-4-[2-(2-hydroxyethoxy)ethyl]-diethylenediamine (referred to generically as hydroxyzine) and its salt derivatives are known to be effective tranquilizers (see U.S. Pat. No. 2,899,436). Acetaminophen is a well known analgesic agent.
The search for analgesic agents of all kinds which will optimize the therapeutic effect and minimize undesired effects has been a long continuing quest in the attempt to find improved treatments. This search has included coadministrations involving analgesics, one with another or with a drug of another type. Among the wide variety of combined administrations which have been considered are those involving a tranquilizer and an analgesic. Such combinations have been mainly of interest in situations where both stress and great pain are anticipated or experienced, such as in surgical situations and the advanced stages of diseases such as cancer. For example, the literature reveals a number of clinical evaluations of the combination of hydroxyzine and a narcotic analgesic, generally co-administered by the i.v. or intramuscular routes, but the results in terms of analgesia have been largely judged to be additive.